Methods and apparatus for compacting powdered metal to form strips



Jan. 17, 1967 M. H. MICHALAK 3,298,060

METHODS AND APPARATUS FOR COMPAGTING POWDERED METAL To FORM STRIPS Filed June 7, 1963 2 Sheets-Sheet 1 j a a/4 1740.55

INVENTORV 'Mar ZL'f/ H Mc/mlak HTTOKNE Y5 Jan. 17, 1967 M. H. MICHALAK 3,298,060

METHODS AND APPARATUS FOR COMPACTING POWDERED METAL TO FORM STRIPS Filed June 7, 1963 2 Sheets-$heet 2 IN VENTOR fwd/"fi l? H MZC/MZQK United States Patent Office 3,298,060 Patented Jan. 17, 1967 3 298,060 METHODS AND APPARATUS FOR COMPACTING POWDERED METAL TO FORM STRIPS Martin H. Michalak, 485 Main St, Westport, Conn. 06880 Filed June 7, 1963, Ser. No. 286,391 Claims. (Cl. 18-9) This invention relates to the art of converting powdered metal into ribbons or strips preparatory to sintering operations.

Heretofore it has been proposed to pass the particles of powdered metal from a hopper to predetermined spaces between a plurality of pairs of laterally spaced rolls with a view to simultaneously producing a plurality of ribbons or narrow strips which may be fed to a furnace in that form for sintering to produce a staple produce. However, the apparatus heretofore proposed for such purpose has been inadequate to produce powdered metal strips for sintering in which the density of the strip of agglomerate is uniform throughout their transverse sections, the inequality being the reduced density in the area of the longitudinal marginal edges of the strip.

An object of this invention is to provide methods and improved apparatus whereby the agglomerate of powdered metal may be compacted to uniform density throughout the width of each strip to the extreme longitudinal edges of the strip. For this purpose, according to the present invention, the powdered metal, while sup plied from a single hopper, is guided by spaced individual chutes to axially spaced pairs of plan cylindrical compacting rolls, the peripheral surfaces of the rolls of each pair being spaced to produce a strip of desired thickness according to the spaces between the rolls of a pair and the ends of the rolls at and in the vicinity of the lines of contact of the rolls with the agglomerate being closed by means traveling with the rolls in the same general di rection and tangential to the lines of contact and having sufficient force and rigidity to resist the lateral movement of the particles at the desired edges of the strips. In this manner, at all points in the width of the strip including the longitudinal edge portions, the density of the agglomerate is maintained uniform and dragging of the particles from the edges of the strip is avoided.

To this end traveling, but substantially unyielding, elements are brought to bear on the ends of the rolls to close the spaces between the rolls at the ends thereof.

A feature of this invention is the provision of spaceclosing means for the ends of the rolls in unit form which may be adjustably mounted to cooperate with the rolls of different widths (to compact strips of different widths) and having means whereby the units may be connected to adjacent units for adjacent pairs of rolls so that they can mutually resist movement away from their respective rolls and independently of their supporting or positioning means.

The advantageous result of this arrangement is that the position of the means for mounting the space-closing means is not critical, any inaccuracy in the positioning of the mounting means being compensated for by the adjustment of the adjacent space-closing means, the one relative to the. other.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

FIGURE 1 is a vertical section of a compacting mill for powdered metal showing the present invention applied thereto.

FIG. 2 is an exploded perspective view showing the edge compacting means of the present invention and the mounting means therefor.

FIG. 3 is a vertical section taken on a line 3-3 of FIG. 4.

FIG. 3A is an elevation of the pressure plate.

FIG. 3B is an elevation of a modified form of pressure plate.

FIG. 4 is a front elevation of a compacting mill showing the present invention applied thereto.

FIG. 5 is a top plan view of the mill shown in FIG. 4 with the hoppers removed.

FIG. 6 is a fragmentary sectional view of another form of coupling device.

The compacting mill of this invention is the exemplification shown in the accompanying drawings comprises a suitable base 10, the upper portion of which is shown in FIG. 1 and side plates 11 in which there are mounted for rotation power driven parallel horizontally spaced and aligned shafts 12 and 13.

According to this invention there are mounted on the shafts 12 and 13 respectively a plurality of pairs of com pacting rolls 15 and 16 axially spaced along the shaft and rotatably driven by the shafts by means of splines 17.

The rolls 15 and 16 of each pair have the same lengths (equal to the width of the powdered metal strip to be formed) and are arranged in pairs with the end faces 18 of each pair aligned in the same vertical plane. The rolls 15 and 16 preferably have the same diameters and are driven in opposite directions so that the upper peripheral surfaces move toward each other and at the same peripheral speeds. As shown inFI'G. 1 the diameters of the rolls and the spacing of the shafts 12 and 13 are such that there is a space or gap between the peripheries of the rolls of determinate width depending on the thickness of the strip to be formed.

The powdered metal is supplied to the mill from a hopper 20 through a plurality of tapering chutes 21 one leading to the gap 19 between each pair of compacting rolls and having bottom opening .22 for discharging the powdered metal into the converging space between the upper portions of the rolls 15 and 16. The ends of the converging space between each pair of rolls is closed by means described below.

Movement of the upper surfaces of the rolls toward each other causes the particles of the powdered metal lying thereon to be compacted as they are drawn into the gap 19 between the rolls and thus form the compacted strip 23 which is guided or carried by suitable means to a sintering furnace or other material treating means not shown.

In order to insure the production of a strip of powdered metal which has uniform density throughout its width even to the longitudinal edge portions, the present invention provides means which engages the end faces 18 of the aligned ends of each pair of rolls 15 and 16 with rigid unyielding means which not only closes the sides of the gap 19 between the rolls and the sides of the converging space between the rolls which receives the powder against escaping laterally from the gap and space, but also travels with the powder and compacted strip in a straight line and in the same direction as the strip thereby assisting the rolls in dragging the powder particles down into the gap at the sides thereof.

For this purpose a gap closing device such as shown in FIG. 2 is provided at each end. of each pair of rolls 15 and 16. This device in the form shown comprises a mounting bracket 24 having a base 25 adapted to be adjustably mounted on and secured to supporting. rails 26, extending between and carried by the side plates 11, by bolts 27 extending through longitudinal slots 28 in the supporting rails 26.

The bracket 24 has a plate 30 secured thereto by screws 31 extending through elongate slots 32 and threaded in holes in the bracket so that the plate may be adjusted vertically. The plate 30 has a pair of upstanding arms 33, the ends of which have semi-cylindrical journals 34 to receive a pair of trunnions 35 on a pressure plate 36.

The pressure plate 36 at each end has a U-shaped recess 37 in which there is rotatably mounted a pulley 38 on a shaft 39, the shaft for the lower pulley 38 extending beyond the sides of the plate 36 and forming the trunnions 35 by which the pressure plate is mounted on the supporting plate 30.

A continuous belt 40 which may be made of canvas or rubbery material or a combination of both surrounds the pressure plate 36 and rides on the pulleys 38. When the plate 36 is forced toward the end faces 18 of the rolls and 16, the belt will engage the rolls and be caused thereby to travel in a straight line in the same direction as the formed strip of metal and at substantially the same speed.

In order to apply sufiicient thrust to the pressure plate 36 to force the belt 40 against the rolls, each pressure plate 36 has a U-shaped yoke 41, the legs 42 of which are attached to the sides of the plate 36 by screws 43 after the belt 40 has been placed around plate 36 and pulleys 38.

The base of the yoke carries a threaded stud 45 which extends perpendicular to the base and which may be welded to the yoke or be otherwise fixed thereto against rotation and it is by means of this threaded stud that the pressure plate 36 may be pressed against the ends of the rolls with a variable force as will be pointed out below.

In the form of the invention shown herein the pairs of rolls 15 and 16 are axially spaced on the shafts 12 and 13 sufficiently to permit the gap closing devices for adjacent pairs of rolls to be inserted in the spaces between the rolls.

In assembling the mill, the brackets are secured to the rails 26 in such position that the belts 40 will lie against the end faces 18 of the rolls 15 and 16. Before being assembled in the machine the adjacent pressure plates 36 are then brought together so that their threaded studs 45 are axially aligned with each other, one of the studs having thereon a coupling 46 with rightand lefthand female threaded ends. The other stud is then screwed into the coupling until the pressure plates are spaced approximately the distance between the ends of the adjacent pairs of rolls. The connected pressure plates are then placed between the pairs of rolls and are mounted respectively on the adjacent supporting plates with the trunnions resting in the journals 34. The vertically adjustable plates 30 at opposite ends of each pair of rolls is then adjusted vertically, if necessary, to place the pressure plates 36 and belts in desired position relative to the nip of the rolls. The coupling 46 is then rotated to force the belt against the end faces 18 of the rolls with a predetermined amount of thrust.

The same procedure is followed in assembling the apparatus with regard to the pressure plates for the outer ends of the end rolls 15 and 16, except that instead of these pressure plates cooperating with another pressure plate of the type illustrated in FIG. 2, the end pressure plates are each connected by a coupling 46a to the stud on a plate 47 which bears against the adjacent side plate 11 of the mill. The plate 47 may be adjusted vertically to align its stud with the stud 45 of the adjacent plate with a screw 48 threaded in a lug 49 in engaging an extension 50 on the plate 47.

After the powdered metal is fed to the chute and by the latter to the converging space above the nip of the rolls and is dragged to and through the nip of the rolls, the force applied to the ends of the rolls by the pressure plates 36 may be varied by adjusting the couplings 46 and 46a to that needed to close the ends of the spaces at the ends of the rolls against the escape of powder while yet permitting the belt 40 to travel with the rotation of the rolls.

The belt 40 is positioned so that its longitudinal center line is approximately in line with the center of the nip of the rolls and is of such width that there is only sufficient contact of the belt with the end faces 18 of the rolls to close the powder collecting and compacting space and form a driving connection between the belt and the ends of the rolls. Since the thrust on the ends of the rolls and compacted strip is not required after the compacted strip passes the nip of the rolls, the recess 37 in the lower end of the pressure plate 36 may be extended upwardly as shown in FIG. 3B.

As shown, the threaded studs 45 are not only axially aligned but are in line with the gaps 19 between the rolls where the greatest contact of the belt with the rolls occurs, thereby obviating any tendency of the pressure plates canting one way or the other.

To permit variation of the thickness of the compacted strip, the shaft 13 for the rolls 16 is mounted in horizontally slidable bearings 51 shown in FIG. 1.

A modification of the means for varying the thrust applied to the pressure plates and hence to the belts is shown in FIG. 6 in which a threaded stud 52 is rigidly secured to one of the yokes 41 while the opposite member (be it another yoke 41 or an end plate 47) is provided with a socket 53 which may be in the form of a hole. Carried by the stud 52 is a cup 54 having internal threads 55 in screw-threaded engagement with the stud 52. The base 56 of the cup has a pin 57 which rotatably fits in the hole 53 of the opposite member. It will be understood that when the cup 54 is rotated, it moves closer to or farther from the yoke 41 and thus produces or reduces the axial thrust on the yoke 41 or its opposite yoke 41 or the plate 47.

In order to avoid the necessity of assembling the adjacent pressure devices before they are placed on their supporting structures, the stud 52 and the cup 54 are of such length and the thread 55 is extended to the base 56 of the cup 54 so that the cup can be screwed far enough toward the yoke 41 to permit the pin 57 to move out of the hole 53 when installing the yoke 41 or the opposing yoke 41 or the plate 47. When the assembly is to be completed, the pin 57 is aligned with the hole 53 and the cup 54 is rotated to cause the base 56 of the cup to engage the opposing member 41 or 47. Thereafter, to control the pressure, the cup 54 is rotated in one direction or the other to increase or decrease the thrust between the opposing members.

It should be understood that, in practicing the present invention, the rolls 15 and 16 need not all be of the same width since it is possible, according to the present invention, to simultaneously make strips of different widths. In changing the mill to simultaneously make widths of different strips, it is merely necessary to remove the shafts and the rolls from the shafts and substitute narrow or wide rolls and then adjust the brackets 24 longitudinally of the frame and substitute, in the case of the form of the invention shown in FIGS. 1 to 5, a longer coupling 46, or, in the case of the form shown in FIG. 6, a longer cup 54.

It will be understood that the belt 40 may be made of, or have on its back surface a coating of, slippery material such as tetrafluoroethylene or, in the alternative, the working face of the pressure plate 47 may have such a coating or insert to reduce the friction between the plate 47 and the belt 40 resulting from the pressure of the pressure plate against the belt.

It will be seen from the above that the present invention provides a simple and efficient compacting means for producing a plurality of narrow powdered metal strips and that, by closing the ends of the compacting space and nip of the rolls by means traveling in a straight line in the direction of the rolls, the lateral edge portions of the strip may have the same density as the central portions.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. Apparatus for compacting powdered metal to form narrow strips or ribbons preparatory to sintering comprising a pair of shafts; a pair of coacting rolls mounted on said shafts, the peripheral surfaces of the rolls being spaced laterally to form a gap having a width depending on the thickness of the strip to be formed and the rolls each having a length equal to the width of the strip to be formed between them; means located at each side of said pair of rolls for applying opposing thrusts to the end faces of the rolls and the lateral edges of the metal powder and compacted strip as the metal powder approaches the gap between the cooperating rolls and passes through said gap, said means for applying thrusts to the ends of said pair of rolls comprising an endless belt engaging end faces of the rolls for closing the ends of the gaps between the rolls, and means for mounting the belt for traveling movement in a straight line in the same direction as the traveling movement of the compacted strip, said thrust applying means further comprising a rigid substantially unyielding pressure plate engaging the belt over an area thereof which is adjacent to the gap and for a substantial distance above the gap, means for supporting the pressure plates adjacent the end faces of the rolls, and means on the supporting means for pivotally supporting each pressure plate for movement toward and from the ends of the rolls.

2. Apparatus for compacting powdered metal according to claim 1, in which there are means on the supporting means for pivotally supporting each pressure plate for movement toward and from the ends of the rolls.

3. Apparatus for compacting powdered metal accord ing to claim 1, in which there are means on the supporting means vertically adjusting the position of the pressure plates relative to the nip of the rolls.

4. Apparatus for compacting powdered metal to form narrow strips or ribbons preparatory to sintering comprising a pair of shafts; a plurality of axially spaced and separated pairs of coacting pressure rolls mounted on said shafts, the peripheral surfaces of the rolls of each pair being spaced laterally to form a gap having a determinate width depending on the thickness of the strip to be formed, and the rolls of each pair having an overall length equal to the width of the strip to be formed between them; and means located at each side of each pair of rolls for applying opposing thrusts to the end faces of the rolls and the lateral edges of the metal powder and compacted strip as the metal powder approaches the gap between the cooperating rolls and passes through said gap, said thrust applying means including axially aligned screw-threaded members aligned with the gaps between adjacent pairs of rolls, and coupling means between the axially aligned screw-threaded members whereby the thrust applied to the end faces of one pair of rolls and the thrust applied to the adjacent end faces of an adjacent pair of rolls may be simultaneously varied and equalized.

5. Apparatus for compacting powdered metal according to claim 4, in which the means for applying thrusts to each pair of pressure rolls includes. screw-threaded means axially aligned with the first-named screw-threaded means and positioned to apply thrust to the end pairs of rolls.

References Cited by the Examiner UNITED STATES PATENTS 2,904,829 9/1959 Heck 18-9 3,010,148 11/1961 Dasher 189 3,017,665 1/1962 Dasher et a1. l89 3,019,487 2/1962 Naeser 264--11 3,144,681 8/1964 Krantz et a1. -18--9 3,152,892 10/1964 Clark 264-11 3,162,708 12/1964 Lund 264--11 3,203,045 8/1965 Naeser et al. 18-9 WILLIAM J. STEPHENSON, Primary Examiner.

ROBERT F. WHITE, Examiner.

J. R. HALL, Assistant Examiner. 

1. APPARATUS FOR COMPACTING POWDERED METAL TO FORM NARROW STRIPS OR RIBBONS PREPARATORY TO SINTERING COMPRISING A PAIR OF SHAFTS; A PAIR OF COACTING ROLLS MOUNTED ON SAID SHAFTS, THE PERIPHERAL SURFACES OF THE ROLLS BEING SPACED LATERIALLY TO FORM A GAP HAVING A WIDTH DEPENDING ON THE THICKNESS OF THE STRIP TO BE FORMED AND THE ROLLS EACH HAVING A LENGTH EQUAL TO THE WIDTH OF THE STRIP TO BE FORMED BETWEEN THEM; MEANS LOCATED AT EACH SIDE OF SAID PAIR ROLLS FOR APPLYING OPPOSING THRUSTS TO THE END FACES OF THE ROLLS AND THE LATERAL EDGES OF THEMETAL POWDER AND COMPACTED STIP AS THE METAL POWDER APPROACHES THE GAP BETWEEN THE COOPERATING ROLLS AND PASSES THROUGH SAID GAP, SAID MEANS FOR APPLYING THRUSTS TO THE ENDS OF SAID PAIR OF ROLLS COMPRISING AN ENDLESS BELT ENGAGING END FACES OF THE ROLLS FOR CLOSING THE ENDS OF THE GAPS BETWEEN THE ROLLS, AND MEANS FOR MOUNTING THE BELT FOR TRAVELING MOVEMENT IN A STRAIGHT LINE IN THE SAME DIRECTION AS THE TRAVELING MOVEMENT OF THE COMPACTED STRIP, SAID THRUST APPLYING MEANS FURTHER COMPRISING A RIGITS SUBSTANTIALLY UNYIELDING PRESSURE PLATE ENGAGING THE BELT OVER AN AREA THEREOF WHICH IS ADJACENT TO THE GAP AND FOR A SUBSTANTIAL DISTANCE ABOVE THE GAP, MEANS FOR SUPPORTING THE PRESSURE PLATES ADJACENT THE END FACES OF THE ROLLS, AND MEANS ON THE SUPPORTING MEANS FOR PIVOTALLY SUPPORTING EACH PRESSURE PLATE FOR MOVEMENT TOWARD AND FROM THE ENDS OF THE ROLLS. 